The war in Iraq is the worst ever for journalists and could spell the end of the "independent witnessing of war", veteran war reporters and experts have claimed.

Twelve journalists have died in the conflict so far. Yesterday a Spanish TV cameraman and a Reuters cameraman were killed when US troops fired on the Palestine Hotel in Baghdad and an al-Jazeera cameraman died when a bomb hit the TV station's office in the city.

Abu Dhabi TV was also hit, which means the US forces have attacked all the main western and Arab media headquarters in the space of just one day.

Four others were wounded in the attack on the hotel - the base for most of the western media in the Iraqi capital - and many other media workers have been injured or gone missing throughout Iraq.

"As we all feared, this conflict has become the worst ever for our profession. Each and every day journalists and media professionals are being killed and injured at an alarming rate," said Chris Cramer, the president of CNN International Networks and the honorary president of the International News Safety Institute.

"Unlike the military, they are all there voluntarily and I hope the public appreciate the risks they're taking to cover the crisis."

Former BBC war correspondent Martin Bell warned the conflict could be the most dangerous yet for journalists.

"I think it's very worrying that independent witnessing of war is becoming increasingly dangerous and this may be the end of it," Bell said.

"I have a feeling that independent journalists have become a target because the management of the information war has become a higher priority than ever."

Another senior BBC journalist, who preferred not to be named, said he was alarmed that the Pentagon did not seem to pay heed to information they had been given by al-Jazeera and every other TV organisation based in the capital.

"I know al-Jazeera gave the Pentagon all their GPS [global positioning system] co-ordinates. It was in a different part of town to the Palestine Hotel and my sources at al-Jazeera are saying the attitude of the Pentagon seemed to be 'maybe we'll take your details'," the journalist said.

The Pentagon's claim that US troops fired at the Palestine Hotel in response to sniper fire has been greeted with incredulity by reporters on the ground, including Sky News' David Chater, and at central command in Qatar.

However, Bell said that for the time being the Americans should be given "the benefit of the doubt".

"I would like to believe this was just a mistake and the Americans did indeed shoot because they believed the building was occupied by snipers," he said.

Andrew Kane, the managing director of AKE Group, which provides safety training to journalists from the BBC and others, said: "It's probably the fastest moving conflict in history. I think it poses bigger problems for journalists because by definition they have to move quickly.

"By the very nature of conflict the very best it can be is organised chaos.

"If you think of the number of friendly fire incidents there have been - bearing in mind that everything that can be done is being done to reduce friendly fire - the fact that innocent people get caught up in it is not unexpected.

"Our advice to media organisations would be to think about where the journalists are positioning themselves in the chaotic centre of the conflict and try to think how they could be perceived by those on the other side."

Owing to the indiscriminate nature of weaponry, journalists should not assume they are safe because they have "press" written on their jackets, Kane said.

"The important thing for the media to do is to dissect and analyse each incident to determine if it could have been a genuine accident - was there any malicious intent, are there lessons to be learned? To walk away from it is not the answer."

Kane said part of the problem is the impression created by politicians that war could be waged with hardly any civilian casualties.

"This is probably the fault of politicians in previous conflicts. Before the Kosovo campaign they almost encouraged the view that you can have a bloodless war," Kane said.

"The military has gone to extraordinary lengths to minimise civilian casualties, probably to the detriment of military operations, yet there are still civilian casualties.

"Because of the idea of a bloodless war people are railing against it. However, in reality the number of civilian casualties is miniscule compared with previous conflicts."

A spokesman for the Ministry of Defence said all wars were dangerous for reporters and insisted journalists have not been targeted by the military.

"Any war is going to be dangerous but it depends where you are and what you're doing. All wars use a lethal level of force but journalists are certainly not a target. We would only ever pick specific military targets," he said.

"The level of access afforded to journalists is greater than ever before. But in terms of saying Iraq's the most dangerous war - how do you quantify that? You can't. There are more journalists covering this conflict with greater access than ever.

"No one's directly targeting them but they've been very, very close to a lot of the action. We would always do our best to afford every protection to embedded journalists."